Effect of pump-1 laser on Autler Townes splitting in photoelectron spectrum of K2 molecule

We theoretically investigate the Autler–Townes(AT)splitting in the photoelectron spectrum of four-level ladder K2molecule driven by a pump 1-pump 2-probe pulse via employing the time-dependent wave packet approach.The effects of the pump-1 laser intensity and wavelength on AT splitting are studied for the first time.The magnitude of AT splitting increases with increasing the pump-1 laser intensity.The triple splitting with asymmetric profile occurs due to the nonresonant excitation.The triple structure is transformed into a double structure(near-resonant region),and then becomes a peak(far-off resonant region)progressively as the pump-1 laser is detuned from the resonance wavelength,which can be explained in terms of the asymmetric excitation/population of dressed states.The splitting between adjacent peaks and the splitting between the two sideband peaks in the triplet do not change with the pump-1 pulse wavelength.The three peaks shift toward lower energy with the same shift 1/4*△1 as the pump-1 wavelength changes in near-resonant region.The asymptotic behaviors of AT splitting with the pump-1 laser intensity are interesting in the threshold points of the near-resonant region and the far-off resonant region.